This invention relates to a vehicle light apparatus using a discharge lamp and an incandescent lamp in combination in that the incandescent lamp is automatically lighting in place of the discharge lamp extinguished when power supply voltage fluctuates.
To supply power to electrical components for a vehicle, voltage generated by an alternator driven by a power source is stabilized by a regulator and is stored in a battery. Thus, there is a possibility that a surge called xe2x80x9cload dumpxe2x80x9d will be caused by a failure or a break in the regulator, a battery contact failure, a rapid decrease in load current, or the like. Measures against the surge are taken for the electric components.
To prevent a failure of a discharge lamp lighting circuit (so-called xe2x80x9cballast circuitxe2x80x9d) when load dump occurs, for example, a headlamp apparatus using a discharge lamp as a light source is provided with a protection circuit to prevent the circuit from operating at higher input voltage than a predetermined level.
However, for example, when load dump occurs during nighttime high-speed driving, if the discharge lamp switches off as the operation of the lighting circuit stops, the driver""s view is lost in an instant and the driver is forced to drive in darkness and thus it is feared that safe driving may be seriously compromised; this is a problem.
It is therefore an object of the invention to ensure the driver""s view by lighting an incandescent lamp in place of a discharge lamp when the discharge lamp is switched off as load dump occurs.
To the end, according to the invention, there is provided a vehicle light apparatus comprising: a discharge lamp as a dipped-beam (low-beam) light source; an incandescent lamp as a substitutional light source of the discharge lamp; a circuit for detecting an input voltage from a power supply becoming equal to or greater than a threshold value in a state that only the discharge lamp is lit and automatically lighting the incandescent lamp.
Therefore, according to the invention, the incandescent lamp for the high-beam light source or the light source of the auxiliary light is lit in place of the discharge lamp switched off if the input voltage from the power supply becomes high, so that the driver""s view can be ensured.